London: Scientists at Saarland University, Germany, have developed a novel sensor technology that will make monitoring long fences possible and can even detect a stealth drone.

The sensors respond immediately as soon as someone tries to climb over or cut through the fence, providing information on the precise location of the security breach. They are even able to detect a low-flying drone passing overhead.

"Our magnetometers (magnetic field sensors) are highly sensitive and can reliably measure even the smallest of changes in the ambient magnetic field," said lead researcher professor Uwe Hartmann.

The thin cable containing the magnetic field sensors can be easily installed on perimeter fences of all kinds.

"The sensors can detect disturbances in the surrounding magnetic field, including the magnetic field above them, with a range extending several metres," said research assistant Haibin Gao.

If someone tries to tamper with a fence, or if they try to climb over it or cut the links with bolt cutters, they will, unavoidably, cause a vibrational disturbance.

The contact-less sensors have low power consumption and are unaffected by rain or fog.

"The sensors function independently of the weather and this gives them a significant advantage over other surveillance techniques, such as cameras, where moisture is often a problem," Hartmann explained.

The cable, which contains the linearly arranged sensors, has a diameter comparable to a standard electrical cable and enables the remote monitoring of miles of perimeter fencing.

The team is collaborating with industrial partners to produce a cable suitable for mass production.

"The cable can be attached to the fence, built into it or even buried beneath it," Hartmann said.

"We are currently working with a number of companies to reduce the size of the system and, most importantly, to lower the cost of producing the sensors to a level where large-volume production becomes feasible," he added.

The research team is currently working on developing the system so that it can recognise the cause of a disturbance and can automatically identify false alarms triggered by wind or animals.